The present invention relates generally to apparatus and methods for testing a plurality of compositions in parallel, and more particularly, to apparatus and methods for testing compositions in contact with a porous medium.
Testing of chemical formulations often involves exposing the chemicals to a porous material such as a fabric which absorbs or interacts with the chemicals. Developers of fabric care products, for example, test different chemical compositions and formulations by exposing pieces of fabric to the compositions or formulations, and measuring the effects on the fabric""s appearance, physical, or chemical properties which result. The types of chemicals or compositions tested in this way may include surfactants, polymers, dyes, bleaches, perfumes, buffers, electrolytes, builders (e.g., calcium sequestering agents), flame retarding agents, and others. Some of the benefits which may be desirable to deliver with such compositions, and which are therefore desirable to measure after exposing the fabric to the compositions or formulations, include release or removal of soils and stains, dye retention by a fabric during washing, prevention of dye transfer from one fabric to another, prevention of soil redeposition, resistance to the abrasion which occurs due to fabrics rubbing against each other during washing, building up of fibers to increase the life of a garment, reduction or prevention of wrinkles, reduction or prevention of static buildup, and improvement or preservation of the feel or texture of a fabric.
Currently used methods of testing for such benefits are extremely laborious, and limit the rate at which new compositions and formulations can be tested. The slowest testing methods involve washing fabrics in conventional full sized washing machines, or doing hand washing in a basin. Some degree of miniaturization has been introduced through the use of instruments such as the Washtec Linitester (manufactured by Roaches) or the Turgotometer (manufactured by Heraeus). In these instruments, washing is done in vessels of reduced volume, typically 0.5-2 liters, and multiple vessels are tested simultaneously. For example, the Heraeus Turgotometer consists of six one liter pots arranged in a straight line, each with an overhead stirrer to provide agitation similar to that found in top-loading washing machines. In the Roaches Washtec, up to twelve 1 liter vessels are mounted radially on a central axel, which is rotated to give an end-over-end tumbling motion and provide agitation. In both cases, the temperature is controlled through a thermostatted bath which surrounds the vessels.
Although these instruments represent a significant improvement over testing methods which utilize full scale washing apparatus, they still require a tremendous amount of manual labor, take up a great deal of space, and have limited throughput. Detergent formulations are extremely complex, often consisting of ten or more ingredients. While significant improvements in detergent performance can be and have been attained by introducing new ingredients or changing formulations, the size of the parameter space to be tested is enormous, including variables related to both chemical structure and formulations. It is therefore, desirable to develop methods and apparatus which allow high-throughput testing of compositions and formulations for fabric care. Ideally, it is desirable to obtain high throughput and miniaturization without sacrificing relevance of the results to more realistic conditions.
One possible method of high throughput testing of fabric care compositions and formulations is to place small, individual pieces of fabric in an array of small vessels, e.g. in a microtiter plate. One drawback to this method is that the individual pieces of fabric are difficult to handle and must be left in the wells during subsequent, handling, treatment, and analysis. If the pieces of fabric are removed from the wells, special handling equipment is required. Also, each piece of fabric may need to be individually labeled to prevent misidentification of the composition used to soak the fabric. Furthermore, it is difficult to simulate the agitation of fabric within a washing machine since the fabric is simply soaking in the fluid.
There is, therefore, a need for an apparatus and method for testing compositions in parallel with a continuous sheet of material having a plurality of porous test regions, which can be easily analyzed upon completion of testing. There is also a need for an apparatus and method for forcing fluid through the porous material or in contact with the material to simulate agitation of the porous material within the fluid.
An apparatus and method for testing compositions in contact with a porous medium are disclosed. The apparatus and method improve the productivity in testing variations of compounds by permitting large numbers of compositions to be tested simultaneously (in xe2x80x9cparallelxe2x80x9d), in an efficient manner that is amenable to various forms of automation to provide high-throughput.
An apparatus for use in testing a plurality of compositions in parallel generally comprises a first plate, a second plate, and a sheet having porous test regions interposed therebetween. The second plate has a plurality of openings extending therethrough to form a plurality of fluid chambers. The test regions are separated by a seal integral with the sheet to prevent fluid transfer between the test regions. The test regions are aligned with the fluid chambers such that each of the chambers is in contact with one of the test regions.
In another aspect of the invention an apparatus for use in performing a plurality of tests in parallel generally comprises a first plate having a plurality of openings extending at least partially therethrough to form fluid chambers and a second plate having a plurality of openings extending at least partially therethrough to form cavities. A sheet having porous test regions is interposed between the first and second plates such that at least a portion of a first surface of the sheet is exposed to the fluid chambers and at least a portion of a second surface of the sheet is exposed to the cavities. The apparatus further includes a flexible membrane positioned between the first and second plates such that changes in pressure within the cavities cause deflection of the membrane away from the sheet to force fluids to pass through the porous test regions.
In another aspect of the invention an apparatus for use in performing a plurality of tests in parallel generally comprises a first plate having openings extending at least partially therethrough to form a plurality of fluid chambers and a second plate having openings extending at least partially therethrough to form a plurality of cavities. A sheet having porous test regions is interposed between the first and second plates such that a first surface of the sheet is at least partially exposed to the fluid chambers. A flexible membrane is positioned between the first and second plates such that changes in pressure within the fluid chambers or cavities cause deflection of the membrane and forces fluid through the porous test region.
In another aspect of the invention, an apparatus for use in performing a plurality of tests in parallel generally comprises a first plate having openings extending at least partially therethrough to form a plurality of fluid chambers and a second plate having openings extending at least partially therethrough to form a plurality of cavities. A flexible membrane is interposed between the first and second plates such that changes in pressure within the cavities cause deflection of the membrane to change pressure within the fluid chamber. The apparatus further comprises a plurality of test materials having different compositions. The plurality of test materials are disposed for fluid communication with the plurality of cavities.
A method for contacting fluid with a porous medium generally comprises supplying a fluid to a plurality of fluid chambers in a test apparatus. The test apparatus generally comprises a first plate defining a plurality of fluid chambers and second plate defining a plurality of cavities aligned with the plurality of fluid chambers. A test sheet is interposed between the first plate and the second plate such that a surface of the test sheet is at least partially exposed to the plurality of fluid chambers. The test sheet includes a plurality of porous test regions aligned with the plurality of fluid chambers. A flexible membrane is interposed between the test sheet and the second plate such that a surface of the flexible membrane is at least partially exposed to the cavities. The method further includes changing pressure within at least one of the plurality of fluid chambers and the plurality of cavities to move the flexible membrane relative to the plurality of chambers or cavities, such that the fluid contacts the plurality of test regions.
In yet another aspect of the invention, an apparatus for use in performing a plurality of tests in parallel generally includes an upper plate having a plurality of openings extending therethrough to form upper fluid chambers and a lower plate having a plurality of openings extending at least partially therethrough to form cavities. A central plate having a plurality of openings extending therethrough to form central fluid chambers is positioned between the upper and lower plates with the central chambers in alignment with the upper chambers and the cavities. A sheet having porous test regions is interposed between the upper and central plates such that an upper surface of the sheet is exposed to the upper chamber and a lower surface of the sheet is exposed to the central chamber. The apparatus further includes a flexible membrane interposed between the lower and central plates such that changes in pressure within the cavities cause deflection of the membrane to force fluid to pass through the porous test regions.
A method of flowing fluid through a porous medium in the apparatus generally comprises changing pressure within the fluid chambers or cavities to move the flexible membrane relative to the porous medium and force fluid therethrough.
The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages, and embodiments of the invention will be apparent to those skilled in the art from the following description, drawings, and claims.